h. samiezadeh

To investigate the effect of deficit irrigation on quantitative and qualitative yield of soybean cultivars, an experiment was conducted as split plots based on randomized complete block design with three replications at agricultural research farm, university of Guilan, during 2009. Main factors were included four irrigation levels based on potential moisture 30-35 (I1), 50-55 (I2), 70-75 (I3) Centibar (irrigation time was determined by tensiometer) and without irrigation (I4), and sub plot factors were included seven soybean cultivars: 033, 032, Sahar (group maturity 4), L.17, Zan, Clark and Madari (group maturity 3). Results showed that seed yield of soybean had decreased in I2 I3 and I4 treatments (15%, 20% and 65% respectively). Among the studied traits, just oil and protein content have increased by drought stress. Highest (1379 Kg) and lowest (478 Kg) seed yield per unit area obtain from I1 and I4, respectively. 033 in I3 treatmenthad the highest and Zan in I4 had the lowest oil and protein yield. Also irrigation water productivity increased significantly with application of deficit irrigation treatments (13% and 33% increment in I2 and I3, respectively). Results of the present experiment showed that in soybean production in Rasht region, irrigation based on potential moisture 70-75 Centibar, moreover in economize of water use and increase in water productivity, can improve of soybean seed oil and protein percentage.

In order to evaluate the effects of deficit irrigation on yield and water productivity of seven soybean cultivars, an experiment was conducted as split plots based on randomized complete block design with three replications at agricultural research farm, Faculty of Agriculture, Guilan University. Main factors of the experiment were four irrigation levels based on soil moisture potential, 30-35 (I1, full irrigation), 50-55 (I2), 70-75 (I3) centibars (measured using tensiometer) and without irrigation (I4). Sub plot factors were included seven soybean cultivars: 033, 032, Sahar (maturity group IV), L.17, Zan, Clark and Madari (maturity group III). Water productivity was calculated based on seed and biological yield. The results showed that deficit irrigation significantly reduced seed yield. The highest and lowest values of the seed yield were obtained in I1 and I4, respectively. But irrigation water productivity significantly increased with application of deficit irrigation treatments (13% and 33% increment in I2 and I3, respectively). During the growing season, treatment I1 received the highest amount of irrigation (2457.14 m3/ha) and also the highest frequency of irrigations (8). According to the ratio of dry matter production to water consumption, water productivity of this treatment (I1) was low. Among all of the irrigation treatments, I3 showed the highest water productivity and there was no significant difference between I2 and I3 for the seed yield. It seemed that I3 had the best water productivity index. Among the studied cultivars, cultivar 033 showed the highest irrigation water productivity (this cultivar had the highest seed yield, as well). According to the results of the present experiment, in Rasht region, combination of treatment I3 and cultivar 033, not only economizes water consumption, increases irrigation efficiency and optimum use of water resources but also produces satisfactory soybean seed yield.

The effects of tillage methods and residual management on yield and yield components of rapeseed (Brassica napus L. CV. Hyola308) were evaluated after rice harvest. The experiment was carried out during 2004-2005 cropping season in a factorical arrangement of treatments at Rice Research Institute of Iran (RRII) in Rasht, in a Complete Randomized Block Design with three replications. Treatments included tillage in three methods a) conventional tillage b) minimum tillage, and c) no tillage, and rice residue management in two manners: a) removing residues, and b) not removing residues. Plant traits such as grain yield, oil percentage and yield, plant density, plant height, the lowest pody branch height from soil surface, number of pods per plant, plant and weed dry weight, leaf area index (LAI) and crop growth rate (CGR) were measured. Results indicated that grain yield was affected by the tillage type. Also, the effect of tillage type on plant height, number of pods per plant, the lowest pody branch height from soil surface, and oil yield was significant. The effect of residual management and residual management interaction and tillage were significant on none of the traits except for weed dry weight. Economic analysis indicated that rapeseed planting in a field with rice residual and minimum tillage had a relative advantage of less production cost in spite of nearly 15 percent yield decrease compared to other methods.